The toxic effects of tobacco smoke, which had been suspect for many years, have now been firmly established by an overwhelming quantity of scientific evidence. Among the various harmful substances when have been shown to be present in tobacco smoke are the various oxides of nitrogen. Of the oxides of nitrogen normally present in tobacco smoke, nitrogen dioxide is the most toxic and most irritating. While the views of experts in the field are at a variance, it is estimated that as much as 50% of the nitrogen oxide content of tobacco smoke is nitrogen dioxide. The total nitrogen oxide content of tobacco smoke has been reported to range from about 145 ppm to about 1000 ppm.
In addition to the irritating and toxic properties of nitrogen dioxide per se in tobacco smoke, it has recently been shown that nitrogen dioxide and certain other oxides of nitrogen can form nitrosating intermediates which in turn can react with susceptible organic amines in the unburned tobacco to form nitrosamines. The phenomenon has been demonstrated by Johnson and Rhoades (J. Nat'l. Cancer Institute 48: 1845-1847, 1972) who reported finding up to 140 ng. of N-dimethyl-nitrosamine per cigarette. The nitrosamine content in the smoke from different types of tobacco can vary from practically none up to 140 ng./cigarette. The amount of nitrosamines present in the smoke of a given type of tobacco is influenced by a number of variables such as, for example, the amount of nitrogen-containing fertilizer used in growing the tobacco plants. N-dimethylnitrosamine is a highly toxic substance and is recognized as a potent carcinogen in animal experiments even at low levels of administration. It is therefore readily apparent that means to effectively reduce the nitrogen dioxide content of tobacco smoke would be of considerable benefit to those individuals who smoke tobacco in some form since reduction in the toxic, irritating nitrogen dioxide also results in a reduction in carcinogenic nitrosamines. Such a means is provided in accordance with the present invention whereby tobacco is treated with a pharmaceutically acceptable salt of ascorbic acid, or erthorbic acid of such salts with their respective acids wherein the molar ratio of acid to salt does not exceed about 3:1.
The effect of smoking on the ascorbic acid content of the human body as well as the benefit heavy smokers might possibly derive from ingestion of large amounts of ascorbic acid have been the subject of a number of reports in the literature. For example, Irwin Stone in his book entitled "The Healing Factor: Vitamin C Against Disease", Grosset & Dunlap, 1972, describes the substantial depletion of vitamin C in the body caused by smoking. The author recommends the ingestion of large amounts of ascorbic acid by heavy smokers for the prevention and treatment of what is termed "smoker's scurvy". This depletion of vitamin C in the body of heavy smokers has been substantiated by numerous others working in the field. These workers also have recommend that heavy smokers consume an abundance of vitamin C to prevent development of a deficiency thereof. These findings and recommendations are directed to the alleviation of one of the harmful effects of heavy smoking in the body, but do not effect the prevention of the formation of nitrosamines or oxides of nitrogen and their presence in the inhaled tobacco smoke.
French Pat. No. 932,560 discloses a device such as cigarette paper, straw-like structure, holder, mouthpiece or similar article with which the smoke comes in contact as it is being inhaled. The device, which may or may not be burned with tobacco, is of a fibrous nature and is either impregnated or covered with a "metabolite" which is stated as being a substance which can interact with normal cell metabolism such as, for example, vitamins including ascorbic acid, enzymes, co-enzymes and the like. French Pat. No. 932,561 discloses treatment of tobacco with such "metabolites". The stated object in having such substances impregnated in or coated on such a device or the tobacco is that these metabolites are thereby mixed with the smoke in appreciable quantities thereby causing them to be inhaled with the smoke. The patents state that the presence of one or more of these metabolites in appreciable quantities in the smoke increases the tolerance of the user to "the toxic products (nicotine)" contained in the smoke. In operation, the metabolites contained in or coated on the device or the tobacco are stated as being progressively volatilized by the heat of combustion and are mixed with and consumed with the smoke.
The stated object of the methods disclosed and claimed in these Frenceh patents is to increase the tolerance of the smoker to the toxic products (nicotine) in the smoke. The teachings of these French patents, therefore, parallel those of Stone and others who have advocated the systemic administration of ascorbic acid to offset the deleterious effects of smoking in that all are concerned with attempting to minimize such effects after the smoke has been inhaled.
It has been found in accordance with the present invention that the amounts of at least one toxic substance, i.e. nitrogen dioxide, which is normally consumed with tobacco smoke can be sharply reduced before the smoke is inhaled.